1. Technical Field
The present invention relates to a method for manufacturing a liquid ejecting head, and more particularly, relates to a method for manufacturing an ink jet recording head which discharges ink as a liquid.
2. Related Art
As an example of an ink jet recording head, which is a liquid ejecting head, there is a recording head including, a channel forming substrate that has a pressure generating chamber communicating with a nozzle orifice and a communicating portion communicating with the pressure generating chamber therein, a piezoelectric element mounted on a surface of the channel forming substrate, and a reservoir forming substrate that has a reservoir portion to be combined with the communicating portion of the channel forming substrate in order to form a part of a reservoir when bonded to the surface of the channel forming substrate having the piezoelectric element thereon. The reservoir mentioned above is constituted by the reservoir portion and the communicating portion which communicate with each other via a through hole portion that passes through a vibration plate and laminated films deposited on the vibration plate (see JP-A-2003-159801 or the like). In JP-A-2003-159801, specifically, a region, which faces the communicating portion, in the vibration plate and laminated films is mechanically punched to form a through hole portion so as to allow the reservoir portion to communicate with the communicating portion.
Mechanical cutting, however, may produce undesirable substances such as contaminant particles during a process of forming a through hole portion, so that the particles mix with ink in channels such as a pressure generating chamber causing problems such as defective ejection. After the formation of the through hole portion, for example, a cleaning process can remove the undesirable substances such as the contaminant particles to some extent, however, it is difficult to remove the particles completely. Furthermore, the mechanical cutting may induce crack formation near the through hole portion, which also may cause defective ejection. That is, if a crack is generated, the ejection from the nozzle orifice using such a reservoir filled with ink may peel off a broken piece from the cracked portion, and the peeled broken piece may clog the nozzle orifice so as to cause defective ejection.
In order to solve the above problems, there is provided a method including processes of removing a region of a vibration plate corresponding to a communicating portion before forming the communicating portion in a channel forming substrate so as to form a through hole portion, sealing the through hole portion with an adhesive layer and a metal layer (hereinafter, a separate metal layer) constituting a lead electrode extending from a piezoelectric element, forming a communicating portion by etching the sealed through hole portion, then removing the adhesive layer and the metal layer by wet etching so as to allow the communicating portion to communicate with the reservoir portion (see JP-A-2006-044083 or the like).
Using such a method for manufacturing the through hole portions such as the reservoir, which penetrates the channel forming substrate and a bonding substrate, the above-mentioned problems with choked nozzle orifices caused by contaminant substances can be avoided. Note here that, however, for example, if nickel-chrome (NiCr) is used as an adhesive layer in the case that gold (Au) is used as a metal layer, for example, an affected layer (a passive layer) may be formed on the surface of the adhesive layer (a separate metal layer) by exposure to an etchant used for etching the channel forming substrate. Once the affected layer is formed on the surface of the adhesive layer, it may be difficult to remove the adhesive layer in a subsequent wet etching process.
Furthermore, as the through hole portions that pass through the channel forming substrate and bonding substrate, there are provided not only the reservoir but also positioning holes that are used to position the channel forming substrate onto the nozzle plate having the nozzle orifice by inserting a positioning pin. The above-mentioned problems, however, may not occur in all adhesive layers disposed at their corresponding through hole portions.
Undoubtedly, such problems, which are found in the method for manufacturing an ink jet recording head for ejecting ink, may also be found in methods for manufacturing other liquid ejecting heads for ejecting liquid other than ink.